BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings which illustrate the preferred embodiments and the best modes presently contemplated for carrying out the present invention:
FIG. 1 is cross-sectional side view of an air-breathing electrostatic ion thruster configured according to a preferred embodiment of the present invention showing atmospheric gas being drawn into the ionization chamber and accelerated ions being discharged therefrom to create thrust; and
FIG. 2 is a schematic view of the electrical circuit for an air-breathing electrostatic ion thruster configured according to a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
With reference to the figures where like elements have been given like numerical designations to facilitate the reader's understanding of the present invention, the preferred embodiments of the present invention are set forth below. As will be readily understood by those skilled in the art, the enclosed figures and drawings are merely illustrative of a preferred embodiment and represents one of several different ways of configuring the present invention. Although specific components, materials, configurations and uses are illustrated, a number of variations to the components and to the configuration of those components described herein and in the accompanying figures can be made without changing the scope and function of the invention set forth herein. For instance, although the figures and description provided herein are directed to a generally cylindrical housing having certain materials and arrangement of components, those skilled in the art will readily understand that this is merely for purposes of simplifying the present disclosure and that the present invention is not so limited.
An air-breathing electrostatic ion thruster that is manufactured out of the components and configured pursuant to a preferred embodiment of the present invention is shown generally as 10 in the figures. Ion thruster 10 generally comprises a housing 12 having a first or forward end 14, a second or rearward end 16, an electrically conductive inner surface 18 and an electrically non-conductive outer surface 20, as shown in FIG. 1. In a preferred embodiment, housing 12 will be made out of a generally lightweight material that has its interior coated with a conductive material to form inner surface 18 and its exterior coated with a non-conductive/insulating material to form outer surface 20. In an alternative embodiment, both inner 18 and outer 20 surfaces are formed from separate cylindrically shaped shells that are joined in abutting relation, with the inner shell, defining inner surface 18, disposed symmetrically within the outer shell, defining outer surface 20, to substantially provide an integral housing 12 having an inner conductive layer and an outer non-conductive layer. Preferably, inner surface 18 will be formed from a metallic material that is known to be highly conductive, such as brass, aluminum, magnesium, copper or like materials. Conversely, outer surface 20 should be formed from an electrically non-conductive, insulating material such as plastic or nylon, with materials such as Delrin, a trademark of DuPont, or the like being preferred due to its resistence to high voltage and high temperature breakdown. Inner surface 18 defines an ionization chamber 22 having an inlet 24 at the forward end 14 of housing 12 and an outlet 26 at the rearward end 16. As explained in more detail below, ambient atmospheric gas 28 is received through inlet 24 and is ionized in ionization chamber 22, with inner surface 18 functioning as an anode (a cylindrical anode in FIG. 1), to discharge accelerated ions 30 through outlet 26 at the rearward end 16 of housing 12 so as to create thrust to propel a vehicle (not shown) utilizing ion thruster 10 of the present invention.
Positioned inside inlet 24, generally at or near forward end 14 of housing 12 and attached thereto, is forward screen electrode 32. In one embodiment, forward screen electrode 32 has a plurality of spaced apart electrically conductive metallic wires or members 34 that define a plurality of forward screen apertures 36 of sufficient size to easily permit atmosphere gas 28 to pass therethrough into ionization chamber 22. Alternatively, forward screen electrode 32 can be other screen or screen-like devices, such as a plate having the plurality of forward screen apertures 36. As explained below, however, the wires or other electrically conductive members 34 forming forward screen electrode 32 must have sufficient surface area to apply an electrical charge thereto. As will be clearly understood by those skilled in the art, a variety of different configurations are possible for forward screen electrode 32, including a typical screen configuration having square, rectangular, circular or oval apertures 36 or formed from metallic or other electrically conductive wires or members 34 that are joined together in a manner that provides sufficient gaps for apertures 36 (i.e., slits or slots similar to blinds, etc.). Positioned inside outlet 26 generally at or near rearward end 16 of housing 12, and attached thereto, is rearward screen electrode 38 having rearward screen apertures 40 and accelerator electrode (or grid) 42 having accelerator apertures 44. As shown in FIG. 1, accelerator electrode 42 is positioned rearward of and in spaced apart relation to, although generally close to, rearward screen electrode 38 in a manner such that the rearward screen apertures 40 are aligned with accelerator apertures 44. As with forward screen electrode 32, the apertures 40 and 44 of both rearward screen electrode 38 and accelerator electrode 42 can be defined by a plurality of metallic wire or other electrically conductive members, shown as 46 and 48, that provide sufficient surface area to apply an electrical charge thereto (alternatively it can be other screen or screen-like devices, such as a plate having the plurality of rearward screen apertures 40). The apertures 40 and 44 of rearward screen electrode 38 and accelerator electrode 42, respectively, should be sufficiently sized and configured to permit the flow of charged, accelerated ions 30 to generally pass therethrough. The function of forward screen electrode 32, rearward screen electrode 38 and accelerator electrode 42 in ion thruster 10 of the present invention is explained below.
Disposed inside ionization chamber 22, preferably near forward screen electrode 32 at inlet 24, is inner electrode 50. As shown in the preferred embodiment of FIG. 1, inner electrode 50 is generally positioned at or near the center of ionization chamber 22 and held in place by insulating struts 52, which preferably connect to inner surface 18 or housing 12. Alternatively, struts 52 can connect to forward screen electrode 38 or rearward screen electrode 38. Various different configurations for inner electrode 50 can be utilized with ion thruster 10 of the present invention. In the preferred embodiment of FIG. 1, inner electrode 50 comprises a support tube 54 connected to struts 52 with a plurality of conductive electrode emitters 56 extending rearward therefrom. In the preferred embodiment, inner electrode 50 is a cathode configured to emit electrons into ionization chamber 22 to ionize the atmospheric gas 28 entering through inlet 24. As explained in more detail below, once the atmospheric gas 28 is ionized it will be drawn toward rearward and accelerated by accelerator screen 42 to displace accelerated ions 30 rearward of ionization chamber 22 to create thrust so as to propel a vehicle utilizing ion thruster 10 of the present invention.
As shown in the schematic of FIG. 2 for the electrical circuit for ion thruster 10 of the present invention, a source of electrical power 58 supplies current to the conductive inner shell (anode) 18, inner electrode 50 and the various electrodes 32, 38 and 42 utilized for ion thruster 10, as well as other components described below. In a preferred embodiment, the source of electrical power 58 is a solar cell array connected to a battery or fuel cell. Alternatively, various other sources of electrical power 58, such as a small generator or the like, which is suitable for the vehicle utilized with ion thruster 10 may be provided as the source of electrical power 58. Preferably, a controller 60 is utilized with ion thruster 10 of the present invention to control the voltages supplied to the various components and the polarity thereof. In a preferred configuration, controller 60 controls the source of electrical power 58 to deliver a first polarity 62, which is positive, to inner surface 18, forward screen electrode 32 and rearward screen electrode 38 and deliver a second polarity 64, which is negative, to accelerator electrode 42 and inner electrode (cathode) 50, as shown in FIG. 2. Alternatively, the polarity supplied by the source of electrical power 58 can be switched so as to be reversed. As well known to those skilled in the art, the electronic signals from controller 60 are preferably controlled by a microprocessor that initiates and regulates the amount of thrust generated by ion thruster 10. As also well known, the controller 60 can be positioned on ion thruster 10, in the vehicle using ion thruster 10 or at a ground station or other remote station. Depending on the desired effects, the various voltages and/or the polarity thereof can be controlled by controller 60 to create the optimal thrust based on the circumstances. In an alternative configuration, ion thruster 10 comprises a plurality of separate sources of electrical power 58 and/or a plurality of separate controllers 60 that individually, but in cooperative fashion, operate the components of ion thruster 10.
In operation, the source of electrical power 58 (as controlled by controller 60) supplies electrical current having a first polarity 62 to inner shell 18, forward screen electrode 32 and rearward screen electrode 38 and supply electrical current having a second polarity 64 to accelerator electrode 42 and inner electrode 50. Ambient atmospheric gas 28 enters ionization chamber 22 through forward screen electrode 32 at inlet 24 to mix with the electrons emitted by the cathode (inner electrode 50) at electrode emitters 56 to generate positively charged ions (in the preferred embodiment with first polarity 62 being positive and second polarity 64 being negative), shown as 66 in FIG. 1. Because the polarity of forward screen electrode 32 is also positive, the forward screen electrode 32 will repel the positively charged ions 66 away from inlet 24 in a generally rearward direction. The positively charged rearward screen electrode 38 and inner surface 18 (having first polarity 62) will attract the electrons from inner electrode/cathode 50 to facilitate mixture thereof with the atmospheric gas 28 to generate positive ions 66. The negatively charged (second polarity 64) accelerator electrode 42 will attract the positively charged ions 66 and accelerate them through the outlet 26 at the rearward end 16 of housing 12 to provide accelerated ions 30 for thrust. The positively charged (first polarity 62) conductive inner surface 18 will maintain the positively charged ions 66 moving rearward in ionization chamber 22. With the preferred solar cell array and battery/fuel cell arrangement for the source of electrical power 58, ion thruster 10 will be able to operate for an extended period of time without additional input of energy.
In the preferred embodiment of ion thruster 10 of the present invention, one or more magnets or series of magnets 68 are positioned outside housing 12, as shown in FIG. 1, or inside ionization chamber 22 to surround portions of the ionization chamber 22. As known to those skilled in the art, magnets 68 can be permanent or electromagnetic, with the latter being preferred, and magnets 68 can be positioned inside chamber 22. If electromagnetic magnets 68 are utilized, they can be electrically connected to the source of electrical power 58 and the amount of current supplied thereto can be regulated by controller 60. The magnetic field produced by magnets 68 will cause the electrons to spiral in a helix shape to obtain improved interaction (i.e., collision) between the electrons and the atmospheric gas 28 to facilitate more efficient and effective formation of the positive ions 66 necessary to provide thrust for ion thruster 10. In addition, the axial magnetic field within ionization chamber 22 created by magnets 68 will tend to restrain the path of the electrons emitted by cathode 50 to inhibit them from being drawn directly to inner surface 18 (the anode), thereby preventing excessive loss of electrons that are needed to form positively charged ions 66 from atmospheric gas 28.
Also in the preferred embodiment, shown in FIG. 1, ion thruster 10 includes a neutralizing mechanism or means 70 near the rearward end 16 of housing 12 (near outlet 26) to interact with the accelerated ions 30 exiting ionization chamber 22 at outlet 26 so as to place the ion thruster 10 in an electrically neutral condition. In the preferred polarity arrangement, with first polarity 62 being positive and second polarity 64 being negative, neutralizing mechanism 70 comprises a negatively charged neutralizer electrode 72 that emits electrons to compensate for the flow of positively charged accelerated ions 30. As shown on FIG. 2, in the preferred embodiment the neutralizer electrodes 72 are electrically connected to the source of electrical power 58 and, also preferably, controlled or regulated by controller 60.
The preferred embodiment of ion thruster 10 of the present invention will incorporate an ozone reduction mechanism (not shown) at or near the rearward end 16 of housing 12 to interact with the discharge gas produced by the ion thruster 10 so as to reduce or even eliminate the ozone that is a by-product of the ionization process. Various other variations are also possible for ion thruster 10. For instance, the size and configuration of housing 12 and the ionization chamber 22 can be varied, as well as the operating voltages, polarity, positioning and size/shape of the electrodes, size and shape of the inlet and/or outlet (i.e., so as to compress the atmospheric air 28 or otherwise tuned for aerodynamic purposes) and the materials used for the various components of ion thruster 10 so as to obtain the most efficient amount of thrust generation for the desired purposes of the vehicle. In addition, the size, placement (including whether inside or outside ionization chamber 22), type (i.e., permanent or electromagnetic magnets), shape and magnetic strength of magnets 68 can be varied.
While there are shown and described herein a specific form of the invention, it will be readily apparent to those skilled in the art that the invention is not so limited, but is susceptible to various modifications and rearrangements in design and materials without departing from the spirit and scope of the invention. In particular, it should be noted that the present invention is subject to modification with regard to any dimensional relationships set forth herein and modifications in assembly, materials, size, shape, and use. For instance, there are numerous components described herein that can be replaced with equivalent functioning components to accomplish the objectives of the present invention.
Patent Application
20080028743
